The study of human hematopoiesis is often limited by the inability to manipulate this process in vivo and differences that exist between humans and commonly employed model organisms. However, human genetics provides a way to gain insight into natural variation in a variety of hematologic phenotypes and creates an opportunity to better understand hematopoiesis. In this review, we discuss how genome-wide association studies are revealing common genetic variation that is associated with hematologic traits and diseases. We discuss how the resulting insight from these studies promises to increase our understanding of human hematopoiesis and outline the challenges that lay ahead in this field.